An engine equipped with a turbocharger (supercharger) drives an exhaust turbine by an exhaust gas flowing through an exhaust passage, supercharges air by a compressor coupled to the exhaust turbine to increase the output of the engine, and is generally equipped with a waste gate valve for adjusting the boost pressure of the turbocharger. Upon opening/closing of the waste gate valve, the following advantages, for example, are obtained: An excessive rise in the boost pressure is suppressed, whereby stability of the boost pressure can be ensured, and damage to the engine or the turbocharger itself can be inhibited. In recent years, it has been common practice to actively control the opening/closing action of the waste gate valve in accordance with the operating state of the engine. There has been, for example, a turbocharger-equipped engine having a first fuel injection valve for injecting fuel to an intake path (intake port) (i.e., port injection valve), and a second fuel injection valve for injecting fuel into a combustion chamber (i.e., cylinder injection valve), wherein in accordance with the operating state of the engine, the cylinder injection valve and the port injection valve are controlled, and a waste gate valve (exhaust bypass valve) is also opened and closed as appropriate (see, for example, Patent Document 1).
This Patent Document 1 discloses a technology which opens the exhaust bypass valve as well as an intake bypass valve, for example, when shifting from a homogeneous lean operation concurrently using supercharging to stratified combustion involving no supercharging.